1. Field of the Invention
The present invention relates to a laser irradiation apparatus, widely used for all kinds of industrial purposes, in particular, for a process of manufacturing an organic light emitting display.
2. Description of the Related Art
An organic light emitting diode can emit light by using an energy discharged while an excited molecule generated when a hole and an electron, which are introduced from two opposite electrodes to an organic light emitting layer, are engaged is returning to the ground state, by locating the organic light emitting layer between the two electrodes and applying voltages to the two electrodes. The organic light emitting display is formed on a base substrate, and a sealing substrate covers an upper portion of the organic light emitting diode.
A main subject in manufacturing the organic light emitting diode is to prevent an external air from penetrating a gap between a substrate on which the organic light emitting diode and a sealing substrate. Korean patent publication No. 10-2006-0005369 discloses a method of sealing a gap between the substrate and the sealing substrate by means of a frit. In Korean patent publication No. 10-2006-0005369, after the sealing substrate is coated with the frit and sintered, and aligned on a base substrate, a laser is irradiated to the frit to seal the substrates in such a way that the frit is melted and cured at the base substrate.
In order to efficiently produce a large amount of organic light emitting displays, a plurality of organic light emitting displays are manufactured on one substrate and cut into individual organic light emitting displays. This is called “sheet unit production”.
The term “sheet unit production” means a method that forms a plurality of organic light emitting displays on a base substrate sheet having a size corresponding to a formation size of the individual organic light emitting displays, coalesces a sealing substrate sheet with the base substrate sheet, and cuts the coalesced substrates suited to individual devices. At this time, when a frit is used as a sealant, the frit is formed corresponding to a position in which individual display devices will be formed.
A coalesced substrate obtained by coalescing a sealing substrate sheet with a base substrate sheet during a process of manufacturing a conventional organic light emitting display in a sheet unit is shown as follows. A sealant is used as a frit. A coalesced substrate sheet includes a base substrate sheet, a sealing substrate sheet, and frits. A plurality of organic light emitting diodes are formed on the base substrate sheet. The sealing substrate sheet coalesces with the base substrate sheet. The frits are disposed between the base substrate sheet and the sealing substrate sheet, and seals the base substrate sheet and the sealing substrate sheet for every organic light emitting diode.
Here, a laser irradiation apparatus is used to coalesce the frit coated and sintered at the sealing substrate sheet with the base substrate sheet. Since a conventional laser irradiation apparatus includes only one laser head, it separately melts and cures the frits one by one. This consumes great time and cost. The conventional laser irradiation apparatus also includes a laser oscillator, and a controller.